Polycarbonate compositions

ABSTRACT

The present invention aims at modifying a polyblend mainly comprising a polycarbdnate resin and a polystyrene resin into a thermoplastic resin composition having flowability and impact strength equivalent to those of a polyblend comprising a polycarbonate resin and an ABS resin, and at providing a harmless flame-retardant thermoplastic resin composition based-on the resulting modified composition. Specifically, the present invention relates to a thermoplastic resin comprising 100 parts by weight of a-resin mixture comprising 30 to 95% by weight of a polycarbonate resin (a), 5 to 70% by weight of a polystyrene resin (b), 0.5 to 20 parts by weight of a specific block copolymer (c) and, if necessary, 0.1 to 20 parts by weight of a polyalkylene terephthalate (d), and/or 0.1 to 20 parts by weight of a polyphenylene ether resin (e), and a flame-retardant thermoplastic resin composition prepared by blending the above composition with 1 to 40 parts by weight of an organophosphorus compound (f) and, if necessary, 0.05 to 5 parts by weight of a fluoroethylene polymer (g).

This is a division of Ser. No. 08/790 746, filed Jan. 27, 1974 now U.S.Pat. No. 6,066,686.

TECHNICAL FIELD TO WHICH THE INVENTION BELONGS

The present invention relates to a thermoplastic resin compositionuseful as the material for the housing, chassis or other members ofoffice automation machines, communication apparatus or domesticelectrical appliances or for automobile members. In particular, thepresent invention relates to a thermoplastic resin composition mainlycomprising a polycarbonate resin and a polystyrene resin and havingexcellent processability, impact resistance and heat stability, and aflame-retardant resin composition based on the above thermoplastic resincomposition.

PRIOR ART

Polycarbonate resins are widely used in industrial fields by virtue oftheir excellent mechanical characteristics and thermal properties.However, the resins have poor processability during molding,particularly in flowability, so that many polyblends of polycarbonateresins with other thermoplastic resins have been developed. Among suchpolyblends, polyblends thereof with acrylonitrile-butadiene-styrene(ABS) resins have been widely used in the fields of automobiles andoffice automation machines, the electronic and electrical fields and soon, for the purposes of improving the flowability and lowing the cost.On the other hand, polyblends thereof with polystyrene are seldom usednow because of their poor mechanical characteristics due to poorcompatibility.

Meanwhile, the synthetic resin materials to be used in the fields ofoffice automation machines, domestic electrical appliances and so on arefurther required to have excellent flame retardance, so that halogenatedflame retardants (such as brominated or chlorinated ones) are frequentlyused as the external flame retardants for the materials. Such flameretardants have a disadvantage of generating corrosive or toxic gasduring processing or burning, though they have a relatively excellentflame retarding effect. Under recent circumstances, where the interestin environmental problems has been increasing, as a means for overcomingthis disadvantage, it has been expected to develop a flame-retardantresin without using a compound containing a halogen (such as bromine orchlorine).

DISCLOSURE OF THE INVENTION

The present invention aims at modifying a polyblend mainly comprising apolycarbonate resin and a polystyrene resin into a thermoplastic resinhaving a flowability and impact strength equivalent to those of apolyblend comprising a polycarbonate resin and an ABS resin, and atproviding a harmless flame-retardant thermoplastic resin compositionbased on the resulting modified composition.

The inventors of the present invention have intensively studied to findthat a resin composition prepared by combining a polycarbonate resinwith a rubber-modified polystyrene resin and adding at least one memberselected from the group consisting of (I) block copolymers (C), whereinboth a polymeric block (A) mainly made from an aromatic vinyl compoundand a polymeric block (B) mainly made from a conjugated diene compoundare present in each molecule, and/or partially hydrogenated derivativesthereof (D), (II) epoxidized block copolymers (E) derived from the blockcopolymers (C) and/or the partially hydrogenated derivatives (D),epoxidized, through the epoxidation of double bonds resulting from theconjugated diene compound, and (III) acid-modified block copolymers (F)derived from the block copolymers (C) and/or the partially hydrogentatedderivatives (D) to the resulting combination is remarkably improved incompatibility and has an excellent flowability and impact strength andthat a resin composition prepared by further adding an organophosphoruscompound and a fluoroethylene polymer to the above resin composition isremarkably improved in flame retardance and impact resistance and issuperior to polyblends of polycarbonate resins withacrylonitrile-butadiene-styrene (ABS) resins in flowability. The abovelongstanding problem has been solved by these findings to therebyaccomplish the present invention.

The present invention relates to a thermoplastic resin compositioncomprising 100 parts by weight of a resin mixture comprising 30 to 95%by weight of a polycarbonate resin (a) and 5 to 70% by weight of apolystyrene resin (b), and 0.5 to 20 parts by weight of at least onemember (c) selected from the group consisting of (I) block copolymers(C), wherein both a polymeric block (A) mainly made from an aromaticvinyl compound and a polymeric block (B) mainly made from a conjugateddiene compound are present in each molecule, and/or partiallyhydrogenated derivatives thereof (D), (II) epoxidized block copolymers(E) derived from the block copolymers (C) and/or the partiallyhydrogenated derivatives (D), epoxidized through the epoxidation ofdouble bonds resulting from the conjugated diene compound, and (III)acid-modified block copolymers (F) derived from the block copolymers (C)and/or the partially hydrogenated derivatives (D).

The present invention includes the following preferred embodiments.Namely, the present invention also relates to the above thermoplasticresin composition wherein the component (b) is a rubber-modifiedpolystyrene resin satisfying the following requirements 1) to 3):

1) the content of rubber in the rubber-modified polystyrene resin is 15to 25% by weight,

2) the volume mean particle diameter of rubber contained in therubber-modified polystyrene resin is 0.3 to 5.0 μm, and

3) the gel content of the rubber-modified polystyrene resin is 15 to 70%by weight.

Further, the present invention relates to a thermoplastic resincomposition as described above which comprises 10 to 94.9% by weight ofthe component (a), 5 to 70% by weight of the component (b) and 0.1 to20% by weight of an aromatic polyester and in which the component (c) isat least one member selected from among the epoxidized block copolymers(II).

The above composition may further contain 0.1 to 20 parts by weight of apolyalkylene terephthalate (d), 0.1 to 20 parts by weight of apolyphenylene ether resin (e), 1 to 40 parts by weight of anorganophosphorus compound (f), 0.05 to 5 parts by weight of afluoroethylene polymer (g) and/or 1 to 150 parts by weight of a flameretardant (i).

An embodiment according to the present invention provides athermoplastic resin composition comprising 100 parts by weight of aresin mixture comprising 30 to 95% by weight of a polycarbonate resin(a) and 5 to 70% by weight of a rubber-modified polystyrene resin (b)satisfying the following requirements 1)to 3):

1) the content of rubber in the rubber-modified polystyrene resin is 15to 25% by weight,

2) the volume mean particle diameter of rubber contained in therubber-modified polystyrene resin is 0.3 to 5.0 μm, and

3) the gel content of the rubber-modified polystyrene resin is 15 to 70%by weight, 0.5 to 20 parts by weight of at least one member (c) selectedfrom the group consisting of (I) block copolymers (C), wherein both apolymeric block (A) mainly made from an aromatic vinyl compound and apolymeric block (B) mainly made from a conjugated diene compound arepresent in each molecule, and/or partially hydrogenated derivativesthereof (D), (II) epoxidized block copolymers (E) derived from the blockcopolymers (C) and/or the partially hydrogenated derivatives (D),epoxidized through the epoxidation of double bonds resulting from theconjugated diene compound, and (III) acid-modified block copolymer (F)derived from the block copolymers (C) and/or the partially hydrogentatedderivatives (D), and, if necessary, 0.1 to 20 parts by weight of apolyalkylene terephthalate (d) and/or 0.1 to 20 parts by weight of apolyphenylene ether resin (e).

Further, the present invention also provides a flame-retardantthermoplastic resin composition comprising the above thermoplastic resincomposition, 1 to 40 parts by weight of an organophosphorus compoundand, if necessary, 0.05 to 5 parts by weight of a fluoroethylenepolymer.

The present invention will now be described in detail.

The term “polycarbonate resin” used in this description for thecomponent (a) refers to a resin prepared by reacting a dihydric phenolwith a carbonate precursor by a solution method or a melting method.

Representative examples of the dihydric phenol to be desirably used inthe preparation of the resin include 2,2-bis(4-hydroxyphenyl)propane(i.e., bisphenol A), bis(4-hydroxyphenyl)methane,1,1-bis(4-hydroxyphenyl)ethane,2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane,2,2-bis(4-hydroxy-3,5-dibromophenyl)propane,2,2-bis(4-hydroxy-3-methylphenyl)propane, bis(4-hydroxyphenyl) sulfideand bis(4-hydroxyphenyl) sulfone. Bis(4-hydroxyphenyl)-alkane typedihydric phenols are more desirable, with bisphenol A being the mostdesirable.

On the other hand, preferable examples of the carbonate precursorinclude carbonyl halides, carbonyl esters and haloformates, and specificexamples thereof include phosgene, diphenyl carbonate, dihaloformates ofdihydric phenols and mixtures of them.

In preparing the polycarbonate resin, one or more of the above dihydricphenols may be used. Further, a mixture of two or more of thepolycarbonate resins thus prepared may be used.

The polystyrene resin to be used in the present invention as thecomponent (b) may be a polymer prepared by polymerizing an aromaticvinyl monomer or a polymer prepared by modifying the polymer with arubber. Examples of the aromatic vinyl monomer used as the unsaturatedmonomer include styrene, methylstyrene, halostyrenes and vinyltoluene.The process for preparing the polystyrene resin is not particularlylimited but may be any known one such as bulk polymerization, solutionpolymerization, suspension polymerization or emulsion polymerization.Preferable examples of the polystyrene resin include polystyrene (GPPS)and high-impact polystyrene (HIPS).

The term “rubber-modified polystyrene resin” used in this descriptionfor the component (b) refers to a polymer comprising a matrix made of anaromatic vinyl polymer and a rubber dispersed in the matrix asparticles, which can be prepared by polymerizing a monomer mixturecomprising an aromatic vinyl monomer in the presence of a rubber by aknown bulk, bulk-suspension, solution or emulsion polymerizationprocess. Examples of the rubber include a low-cis type polybutadiene, ahigh-cis type polybutadiene and styrene-butadiene copolymers, which maybe commercially available ones. Further, two or more of these polymersmay be used simultaneously. Examples of the aromatic vinyl monomerinclude styrene; ring-alkylated styrenes such as o-methylstyrene,p-methylstyrene, m-methylstyrene, 2,4-dimethylstyrene andp-t-butylstyrene; and (α-alkylstyrenes such as α-methylstyrene. Thesemonomers may each be used alone or as a mixture of two or more of them.

The rubber-modified polystyrene resin is particularly preferred tosatisfy the following requirements.

The content of rubber in the rubber-modified polystyrene resin ispreferably within a range of 15 to 25% by weight. When the content isless than 15% by weight, the polyblend of the resulting rubber-modifiedpolystyrene resin with a polycarbonate resin will have a poor impactresistance. On the other hand, when it exceeds 25% by weight, the blendwill have a very poor flowability (processability in molding) and theequipment for preparing the blend will be severely burdened by anincrease in the stirring power or conveying pressure. Further, therubber-modified polystyrene resin may be mixed with a polymer made froman aromatic vinyl monomer and not contain any rubber.

The volume mean particle diameter of rubber contained in therubber-modified polystyrene resin is preferably within a range of 0.3 to5.0 μm. When the volume mean particle diameter is outside this range,the polyblend of the resulting rubber-modified polystyrene resin with apolycarbonate resin will have an unfavorably poor impact resistance andsurface impact strength. The volume mean particle diameter can bedetermined by the use of a 3 wt % solution of a rubber-modifiedpolystyrene resin in methyl ethyl ketone and a particle sizedistribution analyzer of the laser diffraction-scattering type (forexample, LA-700 mfd. by Horiba Seisakusho was used in the Examples whichwill be described below)

The gel content of the rubber-modified polystyrene resin is preferablywithin a range of 15 to 70% by weight. When the gel content is less than15% by weight, the blend of the resulting rubber-modified polystyreneresin with a polycarbonate resin will have an unfavorably poor impactresistance and surface impact strength, while when it exceeds 70% byweight, its flowability (processability during molding) will be verypoor. The term “gel content” used in this description refers to thecontent of toluene insolubles as found in dissolving a rubber-modifiedpolystyrene resin in toluene.

The term “aromatic polyester” used in this description for the component(h) refers to a polyester having aromatic rings in units of thepolymeric chain, which is a homopolymer or copolymer prepared mainlyfrom an aromatic dicarboxylic acid (or an ester-forming derivativethereof) and a diol (or an ester-forming derivative thereof) throughcondensation. Examples of the aromatic dicarboxylic acid include benzenering bearing dicarboxylic acids such as terephthalic acid andisophthalic acid; naphthalene ring bearing ones such asnaphthalene-1,5-dicarboxylic acid and naphthalene-2,6-dicarboxylic acid;and ester-forming derivatives of them. Further, at most, 20 mole % ofthe acid component may be replaced by a dicarboxylic acid other than thearomatic dicarboxylic acids or an ester-forming derivative thereof (forexample, adipic acid or sebacic acid).

Examples of the diol component include aliphatic glycols such asethylene glycol, trimethylene glycol, 1,4-butanediol, hexamethyleneglycol, diethylene glycol and cyclohexanediol; aromatic diols such as1,4-bis(2-hydroxyethoxy)benzene and bisphenol A; and ester-formingderivatives thereof. Preferable examples of the aromatic polyesterinclude polyethylene terephthalate, polytrimethylene terephthalate,poly(1,4-cyclohexanedimethylene terephthalate), polybutyleneterephthalate and copolymers of them, with polybutylene terephthalatebeing particularly preferable. It is generally preferable to use anaromatic polyester having an intrinsic viscosity of 0.5 to 1.6 (asdetermined by the use of o-chlorophenol as solvent at 25° C.).

Detailed description will now be given on component (c), i.e., (I) blockcopolymers (C), wherein both a polymeric block (A) mainly made from anaromatic vinyl compound and a polymeric block (B) mainly made from aconjugated diene compound are present in each molecule, and/or partiallyhydrogenated derivatives thereof (D), (II) epoxidized block copolymers(E) derived from the block copolymers (C) and/or the partiallyhydrogenated derivatives (D) through the epoxidation of double bondsresulting from the conjugated diene compound, and (III) acid-modifiedblock copolymers (F) derived from the block copolymers (C) and/or thepartially hydrogentated derivatives (D).

Examples of the aromatic vinyl compound from which the polymeric block(A) constituting the block polymer (C) is mainly made include styrene,α-methylstyrene, vinyltoluene, p-t-butylstyrene, divinylbenzene,p-methylstyrene and 1,1-diphenylstyrene, among which styrene ispreferably used. Further, these compounds may be used each alone or as amixture of two or more of them.

Examples of the conjugated diene compound from which the polymeric block(B) constituting the block copolymer (C) is mainly made includebutadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene,piperylene, 3-butyl-1,3-octadiene and phenyl-1,3-butadiene. Thesecompounds may be used each alone or as a mixture of two or more of them.Among the compounds, butadiene, isoprene and mixtures of them arepreferable.

The block copolymer (C) is characterized in that both a polymeric block(A) mainly made from an aromatic vinyl compound and a polymeric block(B) mainly made of a conjugated diene compound are present in eachmolecule. It is preferable that the weight ratio of the aromatic vinylcompound to the conjugated diene compound lie between 5/95 and 70/30,still preferably between 10/90 and 60/40.

The molecular structure of the block copolymer (C) may be any oneselected from among linear, branched and radial structures or anycombination of two or more of them. Examples of the molecular structureinclude A-B-A, B-A-B-A, (A-B-)₄Si and A-B-A-B-A wherein A and B meansthe polymeric blocks (A) and (B) respectively. Further, the component(c) may be one derived from the block copolymer (C) through the partialor complete hydrogenation of double bonds resulting from the conjugateddiene compound, i.e., the derivative (D).

It is preferable that the number-average molecular weight of the blockcopolymer (C) be 5,000 to 600,000, still preferably 10,000 to 500,000.Further, it is preferable that the molecular weight distribution [ratioof weight-average molecular weight (Mw) to number-average molecularweight (Mn), i.e., Mw/Mn] be 10 or below. When the number-averagemolecular weight and molecular weight distribution of the blockcopolymer (C) fall within these ranges respectively, the block copolymer(C) can exhibit suitable compatibility with the other components.

The epoxidized block copolymer (E) is prepared by reacting the aboveblock copolymer (C) and/or the partially hydrogenated derivative (D)with an epoxidizing agent such as hydroperoxide or a peroxy acid in aninert solvent. Although the amount of the epoxidizing agent to be usedin the above epoxidation is not strictly limited and may be suitablyselected depending upon the kind of the epoxidizing agent used, thedesired degree of epoxidation and the kind of block copolymer (C) usedas starting material, it is preferable to select the amount of theepoxidizing agent within such a range that the epoxy equivalent of thefinally obtained epoxidized block copolymer (E) falls within a range of140 to 2700, still preferably within a range of 200 to 2000. The term“epoxy equivalent” used in this description refers to a value which iscalculated by the equation: epoxy equivalent=1600/{oxirane oxygencontent (wt%) of epoxidized block copolymer} and which corresponds tothe weight of epoxidized block copolymer per mol of oxirane oxygen.Incidentally, the oxirane oxygen content is determined by titrationusing a solution of hydrogen bromide in acetic acid. A higher epoxyequivalent means a lower oxirane oxygen content, while a lower epoxyequivalent means a higher oxirane oxygen content. When the epoxyequivalent is less than 140, the resulting block copolymer willunfavorably barely exhibit elastic properties, while when it exceeds2700, the resulting block copolymer will unfavorably barely exhibitunique physical properties due to the epoxidation.

The acid-modified block copolymer (F) is prepared by partially modifyingthe above block copolymer (C) and/or the partially hydrogenatedderivative (D) with a carboxylic acid, particularly carboxylic acidanhydride (such as maleic anhydride).

The term “polyalkylene terephthalate” used in this description for thecomponent (d) refers to a product of reaction of an aromaticdicarboxylic acid or a reactive derivative thereof (such as dimethylester or anhydride) with an aliphatic, alicyclic or aromatic diol or amixture of two or more of such products. The polyalkylene terephthalatecan be prepared by conventional processes.

In general, terephthalic acid or dimethyl terephthalate is used as thearomatic dicarboxylic acid or the reactive derivative thereof. Accordingto the present invention, however, the dicarboxylic acid component maycontain, in addition to terephthalic acid, one or more members selectedfrom the group consisting of other C₈-C₁₄ aromatic and alicyclicdicarboxylic acids and C₄-C₁₂ aliphatic dicarboxylic acids, whilespecific examples of the dicarboxylic acid to be used additionallyinclude phthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylicacid, 4,4-diphenyldicarboxylic acid, succinic acid, adipic acid, sebacicacid, azelaic acid and cyclohexane-diacetic acid.

The diol component generally comprises at least one member selected fromthe group consisting of ethylene glycol, 1,4-butanediol and1,4-cyclohexane-dimethylol. The diol component may further contain oneor more members selected from the group consisting of other C₃-C₁₂aliphatic diols and C₆-C₂₁ alicyclic diols in addition to the above diolcompound, while specific examples of the diol to be used additionallyinclude 1,3-propanediol, 2-ethyl-1,3-propanediol, neopentyl glycol,1,5-pentanediol, 1,6-hexanediol, cyclohexane-1,4-dimethylol,3-ethyl-2,4-pentanediol, 2-methyl-2,4-pentanediol,2,2,4-trimethyl-1,4-pentanediol, 2,2,4-trimethyl-1,5-pentanediol,2-ethyl-1,3-hexanediol, 2,2-diethyl-1,3-propanediol, 2,5-hexanediol,1,4-di(β-hydroxyethoxy)benzene, 2,2-bis(4-hydroxycyclohexyl)-propane,2,4-dihydroxy-1,1,3,3-tetramethylcyclobutane,2,2-bis(3-β-hydroxy-ethoxyphenoxy)propane and2,2-bis(4-hydroxypropyl-phenyl)propane.

The polyalkylene terephthalate may be a branched one wherein arelatively small amount of a trihydric or tetrahydric alcohol or atribasic or tetrabasic carboxylic acid is incorporated. The branchedpolyalkylene terephthalate is preferably one wherein one or more membersselected from the group consisting of trimesic acid, trimellitic acid,trimethylolethane, trimethylolpropane and pentaerythritol areincorporated.

Preferable examples of the polyalkylene terephthalate includepolyethylene terephthalate, polybutylene terephthalate,poly(1,4-cyclohexane-dimethylene terephthalate) and copolymers of them.

The term “polyphenylene ether resin” used in this description for thecomponent (e) refers to a homopolymer or copolymer comprising repeatingunits represented by the following general formulae (I) and/or (II):

wherein R₁, R₂, R₃, R₄, R₅ and R₆ are each independently C₁-C₄ alkyl,aryl or hydrogen, with the proviso that the cases wherein both R₅ and R₆are simultaneously hydrogen are excepted.

Representative examples of the polyphenylene ether homopolymer includepoly(2,6-dimethyl-1,4-phenylene) ether,poly(2-methyl-6-ethyl-1,4-phenylene) ether,poly(2,6-diethyl-1,4-phenylene) ether,poly(2-ethyl-6-n-propyl-1,4-phenylene) ether,poly(2,6-di-n-propyl-1,4-phenylene) ether,poly(2-methyl-6-n-butyl-1,4-phenylene) ether,poly(2-ethyl-6-isopropyl-1,4-phenylene) ether andpoly(2-methyl-6-hydroxyethyl-1,4-phenylene) ether, among whichpoly(2,6-dimethyl-1,4-phenylene) ether is particularly preferable.

The polyphenylene ether copolymer may have a phenylene ether structureas the main monomeric unit. Examples thereof include2,6-dimethylphenol/2,3,6-trimethylphenol copolymer,2,6-dimethylphenol/o-cresol copolymer and2,6-dimethylphenol/2,3,6-trimethylphenol/o-cresol copolymer.

The organophosphorus compound (f) to be used in the present invention isnot particularly limited, but may be any organic compound having aphosphorus atom. It is preferable to use an organophosphorus compoundhaving at least one ester oxygen atom directly bonded to the phosphorusatom. This component not only imparts flame retardance to thethermoplastic resin composition of the present invention but also iseffective in improving the impact resistance of the composition.

Examples of the organophosphorus compound usable in the presentinvention include orthophosphates such as trimethyl phosphate, triethylphosphate, tributyl phosphate, tri(2-ethylhexyl) phosphate,tributoxyethyl phosphate, trioleyl phosphate, triphenyl phosphate,tricresyl phosphate, trixylenyl phosphate, tris(isopropylphenyl)phosphate, tris(o-phenylphenyl) phosphate, tris(p-phenylphenyl)phosphate, trinaphthyl phosphate, cresyl diphenyl phosphate, xylenyldiphenyl phosphate, diphenyl (2-ethylhexyl) phosphate,di(isopropylphenyl) phenyl phosphate, o-phenylphenyl dicresyl phosphate,dibutyl phosphate, monobutyl phosphate, di(2-ethylhexyl) phosphate,monoisodecyl phosphate, acid 2-acryloyloxyethyl phosphate, acid2-methacryloyloxyethyl phosphate, diphenyl 2-acryloyloxyethyl phosphateand diphenyl 2-meth-acryloyloxyethyl phosphate; and condensates of thesephosphates, among which triphenyl phosphate is particularly preferable.

The organophosphorus compound usable in the present invention alsoincludes-phosphites such as triphenyl phosphito, trisnonylphenylphosphite, tristridecyl phosphite and dibutyl hydrogen phosphite; andcondensates of these phosphites. Other examples of the organophosphoruscompound include triphenylphosphine oxide, tricresylphosphine oxide,diphenyl methanephosphonate and diethyl phenylphosphonate.

These organophosphorus compounds may each be used alone or as a mixtureof two or more of them.

It is desirable that the fluoroethylene polymer (g) to be used in thepresent invention is a high-molecular one having an Mn value of 10,000or above and a glass transition temperature of −30° C. or above, moredesirably 100° C. or above. The fluorine content of the polymer (g) ispreferably 65 to 76% by weight, still preferably 70 to 76% by weight.Further, it is preferable that the polymer (g) have a mean particlediameter of 0.05 to 1,000 μm, still preferably 0.08 to 20 μm, and adensity of 1.2 to 2.3 g/cm³.

Preferable examples of the fluoroethylene polymer includepolytetrafluoroethylene, polyvinylidene fluoride,tetrafluoroethylenehexafluoropropylene copolymer andethylenetetrafluoroethylene copolymer, among whichpolytetrafluoroethylene is particularly preferable. These polymers mayeach be used alone or as a mixture of two or more of them.

The term “flame-retardant” used for the component (i) includes knownflame-retardants, organic or inorganic compounds having flame retardanceor self-extinguishing characteristics. Examples of the organicflame-retardant include organophosphorus compounds, phosphorus-halogencompounds, and fluoroethylene polymers. Examples of the inorganicflame-retardant include hydroxides of aluminum or magnesium, an antimonycompound, zinc borate, and an zirconium compound. To avoid corrosive ortoxic gas from being generating during processing or burning, it ispreferable to select the flame-retardant without using any compoundcontaining halogen (such as bromine and chlorine). Preferable examplesof the flame-retardant include organo-phosphorus compounds andfluoroethylene polymers.

The proportions of the components in the thermoplastic resin compositionaccording to the present invention will now be described.

The amounts of the polycarbonate resin (a) and the rubber-modifiedpolystyrene resin (b) to be used will first be described. The amount ofthe polycarbonate resin (a) to be used is 30 to 95% by weight,preferably 50 to 90% by weight, still preferably 60 to 80% by weightbased on the resin mixture comprising the polycarbonate resin (a) andthe rubber-modified polystyrene resin (b) (hereinafter referred to as“PC-HIPS resin composition”). When the amount of the resin (a) is lessthan 30% by weight, the thermal deformation temperature will be too low,while when it exceeds 95% by weight, the processability during moldingwill be poor.

The amount of the rubber-modified polystyrene resin (b) to be used is 5to 70% by weight, preferably 10 to 50% by weight, still preferably 20 to40% by weight based on the PC-HIPS resin composition. When the amount ofthe resin (b) is less than 5% by weight, the processability duringmolding will be poor, while when it exceeds 70% by weight, the thermaldeformation temperature will be too low.

The proportions of the components in the thermoplastic resin compositionaccording to the present invention will now be described. The amount ofthe polycarbonate resin (a) to be used is 10 to 94.9% by weight,preferably 50 to 90% by weight, still preferably 60 to 80% weight basedon the resin mixture comprising the polycarbonate resin (a), thepolystyrene resin (b) and the aromatic polyelter (h) (hereinafterreferred to as “PC-PS-APES resin composition”). When the amount of theresin (a) is less than 10% by weight, the thermal deformationtemperature will be too low, while when it exceeds 94.9% by weight, theprocessability in molding will be poor.

The amount of the aromatic polyester (h) to be used is 0.1 to 20% byweight, preferably 0.5 to 10% by weight, still preferably 1 to 5% byweight based on the PC-PS-APES resin composition. When the amount of theresin (h) is less than 0.1% by weight, the strength will be poor, whilewhen it exceeds 20% by weight based on the PC-PS-APES resin composition,the strength will be too low.

Then, the amount of the component (c) selected from the block copolymers(C) to (F) is 0.5 to 20 parts by weight, preferably 1 to 5 parts byweight per 100 parts by weight of the PC-HIPS resin composition. Whenthe amount of the component (c) is less than 0.5 part by weight, theeffect of improving the compatibility of a polycarbonate resin with therubber-modified polystyrene resin will be insufficient and yield athermoplastic resin composition having poor mechanical characteristics.On the other hand, when it exceeds 20 parts by weight, the flameretardance will be affected adversely and the flexural modulus and thethermal deformation temperature will be lowered.

The amount of polyalkylene terephthalate to be used as component (d) is0.1 to 20 parts by weight, preferably 0.5 to 5 parts by weight, per 100parts by weight of the PC-HIPS resin composition. Although the additionof a polyalkylene terephthalate is not essential to the presentinvention, it is effective in enhancing the compatibility of apolycarbonate resin with the rubber-modified polystyrene resin toimprove the surface impact strength. When the amount exceeds 20 parts byweight, the flame retardance will be affected adversely and the Izodimpact strength will be lowered.

The amount of the polyphenylene ether resin to be used as the component(e) is 0.1 to 20 parts by weight, preferably 0.5 to 5 parts by weightper 100 parts by weight of the PC-HTPS resin composition. Although theaddition of a polyphenylene ether resin is not essential to the presentinvention, it is effective in improving the compatibility of apolycarbonate resin with the rubber-modified polystyrene resin toimprove the surface impact strength. Further, the addition is effectivein improving the flame retardance. When the amount exceeds 20 parts byweight, the Izod surface impact strength will be lowered.

When an organophosphorus compound is added to the thermoplastic resincomposition as component (f), the amount thereof is 1 to 40 parts byweight, preferably 5 to 20 parts by weight per 100 parts by weight ofthe PC-HIPS resin composition. When the amount is less than one part byweight, the flame retarding effect will be insufficient, while when theamount exceeds 40 parts by weight, the resulting flame-retardantthermoplastic resin composition will have poor mechanicalcharacteristics.

A fluoroethylene polymer serves as an auxiliary flame retardant for theabove organophosphorus compound and is used as component (g) togetherwith the above organophosphorus compound in the present invention. Theamount of the fluoroethylene polymer to be added to the thermoplasticresin composition of the present invention is preferably 0.05 to 5 partsby weight, still preferably 0.1 to 1 part by weight, per 100 parts byweight of the PC-HIPS resin composition. When the amount falls withinthis range, the dripping due to the plastication of the resins by theadded organophosphorus compound can be inhibited sufficiently and theresulting flame retardant resin composition is not impaired inmechanical characteristics. Incidentally, a flame-retardantthermoplastic resin composition exhibiting flame retardance enough forpractical use and having excellent flowability and impact resistance canbe obtained, even when no fluoroethylene polymer is used.

When a flame-reterdant is added to the thermoplastic resin compositionas the component (i), the amount thereof is 1 to 150 parts by weight,preferably 5 to 80 parts by weight, still preferably 10 to 50% by weightper 100 parts by weight of the PC-PS-APES resin composition. When theamount is less than one part by weight, the flame retarding effect willbe insufficient, while when the amount exceeds 150 parts by weight, theresulting flame-retardant thermoplastic resin composition will have apoor strength.

The thermoplastic resin composition of the present invention and theflame-retardant thermoplastic resin composition comprising it and aflame retardant can be produced by conventional processes. For example,the composition can be produced by premixing predetermined amounts ofnecessary components together by the use of a mixing machine such asHenschel mixer, tumbler, blender, kneader or the like, melt-kneading theobtained premix by the use of an-extruder, heated roll, Banbury mixer orthe like, and pelletizing or grinding the obtained blend. During such aproduction, various additives may be added to the polycarbonate resin orthe rubber-modified polystyrene resin as needed. Examples of suchadditives include fillers, lubricants, reinforcements, stabilizers,light stabilizers, ultraviolet absorbers, plasticizers, antistaticagents, hue improvers and so on.

The thermoplastic resin composition and the flame-retardantthermoplastic resin composition according to the present invention haveexcellent processability during molding, impact resistance, heatstability and flame retardance and can be used as the material for thehousing, chassis or other members of office automation machines,communication apparatus or domestic electrical appliances or forautomobile members.

As described above, a thermoplastic resin composition which has aremarkably improved compatibility and excellent processability duringmolding and impact strength can be obtained by adding a specific blockcopolymer to a polyblend of a polycarbonate resin with a specificrubber-modified polystyrene resin. Further, a novel non-bromine andnon-chlorine flame-retardant thermoplastic resin composition which doesnot generate any corrosive or toxic gas in processing or burning and hasan excellent flame retardance, impact resistance and processabilityduring molding can be obtained by adding an organophosphorus compoundand a fluoroethylene polymer to the above thermoplastic resincomposition.

The present invention makes it possible to use polystyrene as thesubstitute for an ABS resin for the purpose of modifying a polycarbonateresin, though this use was almost impossible in the prior art. Thus, thepresent invention has a high technical and economical value.

EXAMPLE

The present invention will now be described in detail by referring tothe following Examples, though the present invention is not limited bythem. The testing methods will first be described, which were employedin the evaluation experiments made in the following Examples.

(1) Impact strength (unit: kg·cm/cm)

Determined by measuring the Izod impact strength (notched) of a testpiece having a thickness of ¼ inch.

(2) Surface impact strength

(Du Pont impact strength, unit; kgf·cm)

Determined by the use of 1 mm and 2 mm thick test pieces according tothe Du Pont impact strength test wherein the load is 1 kg and the punchdiameter is ¼ inch.

(3) Flame retardance (UL94)

Determined by the use of a test piece (bar sample) having a thickness of{fraction (1/16)} inch according to the vertical flame test (94V-0) asstipulated in UL94 of the UL standards of the United States.

(4) Flowability (unit: mm)

Determined by measuring the distance of flow of each sample in a spiralcavity (flow) [section: 2 mm (thickness)×20 mm (width)] under theconditions of a cylinder temperature of 250° C., mold temperature of 60°C. and injection pressure of 500 kg/cm².

First, the Synthesis Examples will be given, which relate to thepreparation of the rubber-modified polystyrene resins (b) used in thefollowing Examples.

Synthesis Example 1

10 parts by weight of ethylbenzene and 0.005 part by weight ofdi-t-butyl peroxide (DTBPO) were dissolved in 100 parts by weight of asolution of 4 parts by weight of a polybutadiene rubber (a product ofNippon Zeon Co., Ltd., BR1220SG) in 96 parts by weight of monomericstyrene to prepare a feed solution. This feed solution was continuouslyfed into a preheater of the completely stirred mixing tank type andpreheated to 100° C. in the preheater. Then, the resulting feed solutionwas continuously thrown into a first reactor, i.e., a column-type plugflow reactor fitted with a stirrer to conduct polymerization. Thepolymerization temperature in the first reactor was regulated so as togive such a temperature gradient that the temperature increases alongthe direction of flow within a range of 100 to 115° C.

Then, the obtained polymerization mixture was continuously thrown into asecond reactor, i.e., a static mixer type plug flow reactor, and thepolymerization was continued until the conversion of styrene into apolymer reached 82%. The resulting polymerization mixture was thermallytreated in a twin-screw extruder at 230° C. with the volatile componentsbeing removed under a reduced pressure, followed by pelletization. Theobtained rubber-modified polystyrene resin was analyzed. The rubbercontent was 3.8% by weight, the volume mean particle diameter of rubberwas 2.0 μm, and the gel content was 14% by weight. Hereinafter, therubber-modified polystyrene resin obtained in this synthetic example isreferred to as “HIPS-1”.

Synthetic Example 2

10 parts by weight of ethylbenzene and 0.03 part by weight of di-t-butylperoxide (DTBPO) were dissolved in 100 parts by weight of a solution of13 parts by weight of a polybutadiene rubber (a product of UbeIndustries, Ltd., BRZ022) in 87 parts by weight of monomeric styrene toprepare a feed solution. This feed solution was continuously fed into apreheater of the completely stirred mixing tank type and preheated to100° C. in the preheater. Then, the resulting feed solution wascontinuously thrown into a first reactor, i.e., a column-type plug flowreactor fitted with a stirrer to conduct polymerization. Thepolymerization temperature in the first reactor was regulated so as togive such a temperature gradient that the temperature increases alongthe direction of flow within a range of 100 to 115° C.

Then, the obtained polymerization mixture was continuously introducedinto a second reactor, i.e., a static mixer type plug flow reactor, andthe polymerization was continued until the conversion of styrene into apolymer reached 77%. The resulting polymerization mixture was thermallytreated in a twin-screw extruder at 230° C. with the volatile componentsbeing removed under a reduced pressure, followed by pelletization. Theobtained rubber-modified polystyrene resin was analyzed. The rubbercontent was 11.6% by weight, the volume mean particle diameter of rubberwas 2.2 μm, and the gel content was 32% by weight. Hereinafter, therubber-modified polystyrene resin obtained in this synthetic example isreferred to as “HIPS-2”.

Synthetic Example 3

A rubber-modified polystyrene resin was prepared in the same manner asthat of Synthetic Example 2 except that the amounts of the monomericstyrene and the polybutadiene rubber (a product of Ube Industries, Ltd.,BRZ022) were changed to 80 parts by weight and 20 parts by weightrespectively. This rubber-modified polystyrene resin was analyzed. Therubber content was 19% by weight, the volume-mean particle diameter ofthe rubber was 1.8 μm, and the gel content was 41% by weight.Hereinafter, the rubber-modified polystyrene resin obtained in thissynthesis example is referred to as “HIPS-3”.

Synthesis Example 4

A rubber-modified polystyrene resin was prepared in the same manner asthat of Synthetic Example 2 except that the amounts of the monomericstyrene and the polybutadiene rubber (a product of Ube Industries, Ltd.,BRZ022) were changed to 77 parts by weight and 23 parts by weightrespectively. This rubber-modified polystyrene resin was analyzed. Therubber content was 21.5% by weight, the volume-mean particle diameter ofrubber was 2.5 μm, and the gel content was 49% by weight. Hereinafter,the rubber-modified polystyrene resin obtained in this synthesis exampleis referred to as “HIPS-4”.

Next, the preparation of an epoxidized block copolymer will bedescribed. The epoxidized block copolymer is one of the components (c)and was used in the following Examples.

Synthesis Example of an epoxidized block copolymer

300 g of a styrene-butadiene-styrene block copolymer [SBS, a product ofJapan Synthetic Rubber Co., Ltd., TR2000, Mn: ca. 100,000,styrene/butadiene ratio (by weight): 40/60] and 1500 g of ethyl acetatewere charged into a jacketed reactor fitted with a stirrer, a refluxcondenser and a thermometer, followed by dissolution. Then, 169 g of a30 wt % solution of peroxyacetic acid in ethyl acetate was continuouslydropped into the reactor to conduct epoxidation at 40° C. under stirringfor 3 hours. The reaction mixture was brought to room temperature andtaken out of the reactor. A large amount of methanol was added to thereaction mixture to precipitate a polymer. The precipitate was recoveredby filtration, washed with water and dried to obtain an epoxidized blockcopolymer. This copolymer had an epoxy equivalent of 510.

Examples 1 to 16 and Examples 1′ to 7′

According to the formulations (in parts by weight) specified in Tables 1and 2, pelletized resin compositions were each prepared by tumbleblending necessary components and melt kneading the obtained blend bythe use of an extruder, where

a polycarbonate resin made from bisphenol A [a product of TeijinChemicals, Ltd., Panlite L-1225WP] was used as the polycarbonate resin(a),

the above HIPS-1 to 4 were used as the rubber-modified polystyrene resin(b),

a styrene-butadiene-styrene block copolymer (I) [SBS, a product of JapanSynthetic Rubber Co., Ltd., TR2000], the above epoxidized blockcopolymer (II) and maleic anhydride modifiedstyrene/ethylenebutylene/styrene block copolymer (III) [MAH-SEBS, Mn:ca. 100,000, weight ratio of styrene to ethylene-butylene: 30/70, acidvalue: 10 mgCH₃ONa/g] were used as the block copolymer (c),

a poly(1,4-cyclohexanedimethylene terephthalate) containing ethyleneglycol as a comonomer component [PCTG, a product of Eastman Chemical,Easter DN003] was used as the polyalkylene terephthalate (d),

a poly(2,6-dimethyl-1,4-phenylene) ether [a product of GE SpecialtyChemicals, Inc., BLENDEX HPP820] was used as the polyphenylene etherresin (e),

triphenyl phosphate and a condensed phosphate ester represented by thefollowing chemical formula (III) [a product of Daihachi ChemicalIndustry Co., Ltd., PX-200] were used as the organophosphorus compound(f),

polytetrafluoroethylene [a product of Du Pont-Mitsui FluorochemicalsCo., Ltd., Teflon 6-J] was used as the fluoroethylene polymer (g), and

“Cevian V520” [a product of Daicel Chemical Industries, Ltd.) was usedas the ABS resin.

Then, these pelletized resin compositions were each molded into testpieces for general physical properties by the use of an injectionmolding machine (cylinder temp.: 240° C., mold temp.: 60° C.) andexamined according to the usual methods. The results are given in Tables1 and 2.

TABLE 1 Ex. Ex. 1 2 3 4 5 6 7 8 1′ 2′ 3′ 4′ Components of PanliteL-1225WP 80 80 80 80 80 80 80 70 80 80 80 80 thermoplastic HIPS-1 20resin compn. HIPS-2 20 (pt. wt.) HIPS-3 20 20 20 20 20 20 30 20 HIPS-420 TR2000 3 epoxidized block 3 3 3 3 3 3 3 3 copolymer MAH-SEBS 3 EasterDN003 1 1 BULENDEX HPP820 1 1 Cevian V520 20 Results of Izod impactstrength 72 80 75 68 68 40 36 52 29 42 7 45 evaluation (kg · cm/cm) DuPont impact strength 50 or 50 or 50 or 50 or 50 or 50 or 50 or 50 or 10or 10 or 10 or 50 or (thickness: 2 mm) above above above above aboveabove above above below below below above (kgf · cm) Du Pont impactstrength 17 21 15 14 20 27 24 11 10 or 10 or 10 or 26 (thickness: 1 mm)below below below (kgf · cm) flowability (mm) 115 113 119 117 113 111109 130 122 121 124 99

TABLE 2 Ex. Ex. 9 10 11 12 13 14 15 16 5′ 6′ 7′ Components of PanliteL-1225WP 80 80 80 80 80 80 80 70 80 80 80 thermoplastic HIPS-1 20 resincompn. HIPS-3 20 20 20 20 20 20 20 30 20 (pt. wt.) TR2000 3 epoxidizedblock 3 3 3 3 3 3 3 3 copolymer Easter DN003 1 1 BULENDEX HPP820 1 1triphenyl phosphate 12 12 12 12 10 10 14 12 12 12 PX-200 15 Teflon 6-J0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Cevian V520 20 Results of Izodimpact strength 42 38 32 45 37 20 15 28 16 3 18 evaluation (kg · cm/cm)Du Pont impact strength 50 or 50 or 50 or 50 or 50 or 50 or 50 or 50 or10 or 10 or 50 or (thickness: 2 mm) above above above above above aboveabove above below below above (kgf · cm) Du Pont impact strength 13 1210 14 11 22 20 10 10 or 10 or 19 (thickness: 1 mm) below below (kgf ·cm) flame retardance (UL94) V-2 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0flowability (mm) 225 217 226 222 219 210 212 239 226 230 198

<Evaluation of the test results>

{circle around (1)} The thermoplastic resin composition of the presentinvention mainly comprising a polycarbonate resin and a specificrubber-modified polystyrene resin is nearly equivalent to a polyblend ofa polycarbonate resin with an ABS resin in impact strength, and issuperior to the polyblend in flowability (processability duringmolding).

{circle around (2)} The flame-retardant thermoplastic resin compositionof the present invention is equivalent to a polyblend of a polycarbonatewith an ABS resin having a composition corresponding to that of theresin composition in impact resistance, and is superior to the polyblendin flame retardance and flowability (processability during molding).

It has been proved that these effects can be attained only when theblock copolymer (c) is added to a polycarbonate resin compositioncontaining the specific rubber-modified polystyrene resin (b) accordingto the present invention.

Examples 17 to 23 and Examples 8′ to 18′

“Panlite L-1225WP” (a product of Teijin Chemicals, Ltd.) was used as thepolycarbonate resin, a high-impact polystyrene (a product of DaicelChemical Industires, Ltd., “Daicel Styrol S81”) was used as thepolystyrene resin, a polybutylene terephthalate (a product ofPolyplastics Co., Ltd., “Duranex 400FP”) and a polyethyleneterephthalate (a product of Mitsubishi Rayon Co., Ltd., “DianiteMA-521”) were used as the aromatic polyester, and a product obtained bythe following process was used as the epoxidized block copolymer.Namely, 300 g of a polystyrene-polybutadiene-polystyrene block copolymer[a product of Japan Synthetic Rubber Co., Ltd., trade name: TR2000] and1500 g of ethyl acetate were charged into a jacketed reactor fitted witha stirrer, a reflux condenser and a thermometer, followed bydissolution. Then, 169 g of a 30 wt % solution of peroxyacetic acid inethyl acetate was continuously dropped into the reactor to conductepoxidation at 40° C. under stirring for 3 hours. The reaction mixturewas brought to room temperature and taken out of the reactor. A largeamount of methanol was added to the reaction mixture to precipitate apolymer. The precipitate was recovered by filtration, washed with waterand dried to obtain an epoxidized block copolymer. This block copolymerhad an epoxy equivalent of 510. Further, “Cevian V520” (a product ofDaicel Chemical Industries, Ltd.) was used as the ABS resin; triphenylphosphate, trixylenyl phosphate (a product of Daihachi Chemical IndustryCo., Ltd. “PX-130”) and a condensed phosphate ester of the abovechemical formula (III) (a product of Daihachi Chemical Industry Co.,Ltd., “PX-200) were used as the organophosphorus compound; and “Teflon6-J” (a product of Du Pont-Mitsui Fluorochemicals Co., Ltd.) was used asthe fluoroethylene polymer. According to the formulations (in parts byweight) specified in Tables 3 and 4, pelletized resin compositions wereeach prepared by tumble blending the necessary components and meltkneading the obtained blend by the use of an extruder and molding intotest pieces for general physical properties by the use of an injectionmolding machine (cylinder temp.: 250° C., mold temp.: 60° C.). Thesetest pieces were examined for various properties according to the usualmethods. The results are given in Tables 3 and 4.

TABLE 3 (pt. by wt.) Ex. 17 18 19 20 21 22 23 Polycarbonate 80 80 80 8080 80 70 resin*¹ polystyrene resin*² 20 20 20 20 20 20 30 aromatic 1 1 11 1 1 polyester (1)*³ aromatic 1 polyester (2)*⁴ epoxidized block 3 3 33 3 3 3 copolymer*⁵ organophosphorus 12 12 12 13 compd. (1)*⁶organophosphorus 14 compd. (2)*⁷ organophosphorus 15 compd. (3)*⁸fluoroethylene 0.5 0.5 0.5 0.5 0.5 polymer*⁹ Izod impact strength 42 1413 14 12 11 9 (kg · cm/cm) Du Pont impact 50 or 50 or 50 or 50 or 50 or50 or 50 or strength above above above above above above above (kgf ·cm) flame retardance HB V-2 V-0 V-0 V-0 V-0 V-0 (UL94) flowability (mm)127 225 220 221 216 224 249 *¹a product of Teijon Chemicals, Ltd.,“Panlite L-1225WP” *²a product of Daicel Chemical Industries, Ltd.,high-impact polystyrene “Daicel Styrol S81” *³a product of PolyplasticsCo., Ltd., polybutylene terephthalate “Duranex 400FP” *⁴a product ofMitsubishi Rayon Co., Ltd., polyethylene terephthalate “Dianite MA-521”*⁵a product synthesized in laboratory *⁶a product of Daihachi ChemicalIndustry Co., Ltd., triphenyl phosphate *⁷a product of Daihachi ChemicalIndustry Co., Ltd., trixylenyl phosphate “PX-130” *⁸a product ofDaihachi Chemical Industry Co., Ltd. having a structure of the chemicalformula (III), “PX-200” *⁹a product of Du Pont-Mitsui FluorochemicalsCo., Ltd., “Telfon 6-J”

TABLE 4 (pt. by wt.) Ex. 8′ 9′ 10′ 11′ 12′ 13′ 14′ 15′ 16′ 17′ 18′Polycarbonate 80 80 80 80 80 80 80 70 80 80 80 resin*¹ polystyrene 20 2020 20 20 20 20 30 resin*² aromatic 1 polyester*³ epoxidized block 3 3 33 3 copolymer*⁵ ABS resin*¹⁰ 20 20 20 organophosphorus 12 12 12 13 12compd. (1)*⁶ organophosphorus 14 compd. (2)*⁷ organophosphorus 15 15compd. (3)*⁸ fluoroethylene 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 polymer*⁹Izod impact 10 41 3 2 16 12 12 10 45 18 12 strength (kg · cm/cm) Du Pontimpact 10 or 10 or 10 or 10 or 10 or 10 or 10 or 10 or 50 or 50 or 50 orstrength below below below below below below below below above aboveabove (kgf · cm) flame retardance HB HB V-0 V-0 V-0 V-0 V-0 V-0 HB V-0V-0 (UL94) flowability (mm) 137 129 230 229 224 219 223 248 108 198 171*¹⁰a product of Daicel Chemical Industries, Ltd., “Cevian V520”

<Evaluation of the test results>

{circle around (1)} The thermoplastic resin composition of the presentinvention mainly comprising a polycarbonate resin and a specificrubber-modified polystyrene resin is nearly equivalent to a polyblend ofa polycarbonate resin with an ABS resin in impact strength, and issuperior to the polyblend in flowability (processability duringmolding).

{circle around (2)} The flame-retardant thermoplastic resin compositionof the present invention is equivalent to a polyblend of a polycarbonatewith an ABS resin having a composition corresponding to that of theresin composition in impact resistance, and is superior to the polyblendin flame retardance and flowability (processability during molding).

It has been proved that these effects can be attained only when both theepoxidized block copolymer and an aromatic polyester are simultaneouslyused.

Examples 24 to 28 and Examples 19′ to 23′

A high-impact polystyrene “Daicel Styrol S81” (trade name, a product ofDaicel Chemical Industries, Ltd.) was used as the polystyrene resin;“Panlite L-1225WP” (trade name, a product of Teijin Chemicals, Ltd.) wasused as the polycarbonate resin; “ESBS420” (trade name, a product ofDaicol Chemical industries, Ltd.) was used as the epoxidized blockcopolymer; “Cevian V520” (trade name, a product of Daicel ChemicalIndustries, Ltd.) was used as the ABS resin; triphenyl phosphate, PX-130and PX-200 (trade names, products of Daihachi Chemical Industry Co.,Ltd.) were used as the organophosphorus compound; and “Teflon 6-J”(trade name, a product of Du Pont-Mitsui Fluorochemicals Co., Ltd.) wasused as the fluoroethylene polymer. According to the formulationsspecified in Table 5, pelletized resin compositions were each preparedby tumble blending the necessary components and melt kneading theobtained blend by the use of an extruder, and molding into test piecesfor general physical properties by the use of an injection moldingmachine (cylinder temp.: 240° C., mold temp.: 60° C.). These test pieceswere examined for various properties according to the usual methods. Theresults are given in Table 5.

TABLE 5 Ex. Ex. 24 25 26 27 28 19′ 20′ 21′ 22′ 23′ Cevian V520 20 20Daicel Styrol S81 20 20 20 20 20 20 20 20 Panlite L-1225WP 80 80 80 8080 80 80 80 80 80 ESBS420 5 5 5 5 5 triphenyl phosphate 14 14 14 14PX-130 15 15 15 PX-200 15 Teflon 6-J 0.4 0.4 0.4 0.4 0.4 0.4 0.4 Izodimpact 45 10 10 18 12 10 3 4 15 17 strength (kg · cm/cm) flameretardance HB V-2 V-0 V-0 V-0 HB V-0 V-0 V-0 V-0 (UL94) flowability (mm)129 237 235 226 196 137 248 240 214 192

<Evaluation of the test results>

{circle around (1)} The thermoplastic resin composition of the presentinvention mainly comprising a polycarbonate resin and a polystyreneresin is nearly equivalent toga polyblend of a polycarbonate resin withan ABS resin in impact strength, and is superior to the polyblend duringflowability (processability in molding).

{circle around (2)} The flame-retardant thermoplastic resin compositionof the present invention is equivalent to a polyblend of a polycarbonatewith an ABS resin having a composition corresponding to that of theresin composition in impact resistance, and is superior to the polyblendin flame retardance and flowability (processability during molding).

It has been proven that these effects can be attained only when both theepoxidized block copolymer and a fluoroethylene polymer aresimultaneously used.

What is claimed is:
 1. A thermoplastic resin composition comprising 100 parts by weight of a mixture comprising 30 to 95% by weight of a polycarbonate resin (a) and 5 to 70% by weight of a high-impact polystyrene resin (b) having a rubber content of 15-25%, a particle size of 0.3-5.0 μm and a gel content of 15-70 wt. % and 0.5 to 20 parts by weight of block copolymers (c) having a polymeric block (A) mainly made from an aromatic vinyl compound and a polymeric block (B) mainly made from a conjugated diene compound, and/or partially hydrogenated derivatives thereof (D) are present in each molecule, 0.1 to 20 parts by weight of a polyphenylene ether resin (e) and 1 to 40 parts by weight of an organophosphorus compound (f) selected from the group consisting of

and a mixture of at least one of triphenylphosphate and trixylenylphosphate and


2. The thermoplastic resin composition of claim 1, wherein the organophosphorus compound (f) is


3. The thermoplastic resin composition of claim 1, wherein the organophosphorus compound (f) is a mixture of at least one of triphenylphosphate and trixylenylphosphate and


4. The thermoplastic resin composition of claim 1, additionally comprising 0.05 to 5 parts by weight of a fluoroethylene polymer (g).
 5. The thermoplastic resin composition of claim 4, wherein the fluoroethylene polymer (g) is polytetrafluoroethylene. 